The food industry uses bacteria in order to improve the taste and the texture of foods and also to extend the shelf life of these foods. In the case of the dairy industry, lactic bacteria are commonly used in order to, for example, bring about the acidification of milk (by fermentation) and to texturize the product into which they are incorporated. Among the lactic bacteria commonly used in the food industry, examples include the genera Streptococcus, Lactococcus, Lactobacillus, Leuconostoc, Pediococcus and Bifidobacterium. 
The lactic acid bacteria of the species Streptococcus thermophilus are used extensively alone or in combination with other bacteria for the production of food products, in particular fermented products. They are used in particular in the formulation of the ferments used for the production of fermented milks, for example yogurts. Certain bacteria play a dominant role in the development of the texture of the fermented product. This characteristic is closely linked to the production of polysaccharides. Among the strains of Streptococcus thermophilus it is possible to distinguish texturizing and non-texturizing strains.
In addition, cultures—such as starter cultures—are used extensively in the food industry in the manufacture of fermented products including milk products (such as yoghurt, butter and cheese), meat products, bakery products, wine and vegetable products. The preparation of cultures is labour intensive, occupying much space and equipment, and there is a considerable risk of contamination with spoilage bacteria and/or phages during the step of propagation. The failure of bacterial cultures by bacteriophage (phage) infection and multiplication is a major problem with the industrial use of bacterial cultures. There are many different types of phages with varying mechanisms to attack bacteria. Moreover, new strains of bacteriophages appear.
Strategies used in industry to minimise bacteriophage infection, and thus failure of a bacterial culture, include the use of: (i) mixed starter cultures; and (ii) the alternate use of strains having different phage susceptibility profiles (strain rotation).    (i) Traditionally, starter cultures in the dairy industry are mixtures of lactic acid bacterial strains. The complex composition of mixed starter cultures ensures that a certain level of resistance to phage attack is present. However, repeated sub-culturing of mixed strain cultures leads to unpredictable changes in the distribution of individual strains and eventually undesired strain dominance. This in turn may lead to increased susceptibility to phage attack and risk of fermentation failures.    (ii) The rotation of selected bacterial strains which are sensitive to different phages is another approach to limit phage development. However, it is difficult and cumbersome to identify and select a sufficient number of strains having different phage type profiles to provide an efficient and reliable rotation program. In addition, the continuous use of strains requires careful monitoring for new infectious phages and the need to quickly substitute a strain which is infected by the new bacteriophage by a resistant strain. In manufacturing plants where large quantities of bulk starter cultures are made ahead of time, such a quick response is usually not possible.
There is a continuing need in the art to provide improved bacterial strains for use in the food/feed industry—such as bacterial strains that have improved texturizing properties. Improved bacterial strains that are phage resistant are particularly desirable.